In order to be able to park several aircraft alongside one another in an airport terminal, an aircraft hangar or any other building, it is important to be able to accurately guide the aircraft in maneuvers on the ground. In effect, the space available between each aircraft can be of the order of thirty or so centimetres whereas an aircraft wing span can typically be more than sixty metres.
Conventionally, in order to assist an operator of an aircraft tractor in positioning an aircraft with sufficient accuracy, plumb lines are fixed to anchor points located under the fuselage of the aircraft, in the plane of symmetry of the fuselage. The plumb lines thus make it possible to show the plane of symmetry of the fuselage on the ground. The operator of the aircraft tractor can then align this plane of symmetry shown by plumb lines with a marking on the ground in order to position the aircraft. Furthermore, targets on the marking on the ground make it possible to position the aircraft on the axis defined by the marking on the ground by indicating the final position of the plumb lines, the plumb lines then having to be directly above the targets.
FIG. 1 shows, for example, an airport terminal comprising several placements 100, 101 and 103 intended to accommodate the aircraft 110, 111 and 112. Markings on the ground 120, 121 and 122 define theoretical position of the planes of symmetry of the fuselage of the aircraft 110, 111 and 112 correctly positioned in their respective placements 100, 101 and 102. The aircraft 111, in its stop or parking position, is parked between the aircraft 110 and 112. The aircraft 111 has potentially little space to be correctly positioned in its placement 101 while remaining away from the aircraft 110 and 112 parked alongside. As has been stated, in practice, the distances D1 and D2—D1 representing the distance between the aircraft 110 and 111 and D2 the distance between the aircraft 111 and 112—can thus be of the order of thirty or so centimetres whereas an aircraft wing span can typically be more than sixty metres. An operator of an aircraft tractor used to move the aircraft 111 must therefore have a visual aid or a system for assisting in the guiding of the aircraft 111 in order to be able to perform the operation of positioning this aircraft 111 between the aircraft 110 and 112 with the necessary degree of accuracy.
FIG. 2 is an illustration of a known system for assisting in the guiding of an aircraft on the ground. Conventionally, plumb lines 201 and 202 are used. The plumb lines 201 and 202 are fixed to anchor points present under the fuselage, located in the plane of symmetry of the fuselage, at the front and at the rear of the aircraft 111 and so as to show the vertical plane containing the longitudinal axis of the aircraft 111. These plumb lines 201 and 202 allow an operator driving an aircraft tractor 210 used to move the aircraft 111 to see the position of the axis of the aircraft 111 relative to the marking on the ground 121. Thus, the operator seeing the plumb lines 201 and 202 above the marking 121 makes it possible for the operator to ensure that the axis of the aircraft 111 is indeed in the vertical plane defined by the marking on the ground 121, thus guaranteeing that the ends of the wings of the aircraft 111 will not touch the aircraft 110 or 112. The positioning of the aircraft 111 on the longitudinal axis defines by the marking on the ground 121 is done by marking out two targets (not represented) on the ground, each target defining a vertical position for the plumb lines 201 and 202 fixed under the fuselage of the aircraft 111. Thus, the positioning of the targets on the axis 121 makes it possible to adjust the position of the nose of the aircraft 111 relative to its placement 101.
Although such a system is satisfactory, it is sensitive to disturbances provoked by the movements of the aircraft or by the wind, disturbances which can cause oscillations of the plumb lines and thus slow down the positioning manoeuvre. It is in fact necessary to wait for the oscillations of the plumb lines to stop to use the system for assisting in the guiding of an aircraft on the ground described previously.
Patent application US 2009/182506 A1 discloses a collision-preventing system for airplane moving on ground; such system is nevertheless not adapted for assisting in the guiding of an aircraft on the ground by an aircraft tractor.